| head {utils} | R Documentation |
Return the First or Last Part of an Object
Description
Returns the first or last parts of a vector, matrix, table, data frame
or function. Since head() and tail() are generic
functions, they may also have been extended to other classes.
Usage
head(x, ...)
## Default S3 method:
head(x, n = 6L, ...)
## S3 method for class 'data.frame'
head(x, n = 6L, ...)
## S3 method for class 'matrix'
head(x, n = 6L, ...)
## S3 method for class 'ftable'
head(x, n = 6L, ...)
## S3 method for class 'table'
head(x, n = 6L, ...)
## S3 method for class 'function'
head(x, n = 6L, ...)
tail(x, ...)
## Default S3 method:
tail(x, n = 6L, ...)
## S3 method for class 'data.frame'
tail(x, n = 6L, ...)
## S3 method for class 'matrix'
tail(x, n = 6L, addrownums = TRUE, ...)
## S3 method for class 'ftable'
tail(x, n = 6L, addrownums = FALSE, ...)
## S3 method for class 'table'
tail(x, n = 6L, addrownums = TRUE, ...)
## S3 method for class 'function'
tail(x, n = 6L, ...)
Arguments
x |
an object |
n |
a single integer. If positive, size for the resulting
object: number of elements for a vector (including lists), rows for
a matrix or data frame or lines for a function. If negative, all but
the |
addrownums |
if there are no row names, create them from the row numbers. |
... |
arguments to be passed to or from other methods. |
Details
For matrices, 2-dim tables and data frames, head() (tail()) returns
the first (last) n rows when n > 0 or all but the
last (first) n rows when n < 0. head.matrix() and
tail.matrix() are exported. For functions, the
lines of the deparsed function are returned as character strings.
If a matrix has no row names, then tail() will add row names of
the form "[n,]" to the result, so that it looks similar to the
last lines of x when printed. Setting addrownums =
FALSE suppresses this behaviour.
Value
An object (usually) like x but generally smaller. For
ftable objects x, a transformed format(x).
Author(s)
Patrick Burns, improved and corrected by R-Core. Negative argument added by Vincent Goulet.
Examples
head(letters)
head(letters, n = -6L)
head(freeny.x, n = 10L)
head(freeny.y)
tail(letters)
tail(letters, n = -6L)
tail(freeny.x)
tail(freeny.y)
tail(library)
head(stats::ftable(Titanic))